Electric-arc lamp.



No. 762,115. I PATENTED JUNE 7, 1904.

M. H. BAKER & s. P. WILBUR.

ELECTRIC ARC LAMP.

APPLICATION FILED DBO. 6, 1902- H0 MODEL. 2 SHEETS-SHEET 1.

PATENTED JUNE 7, 1904. M. H. BAKER & S. P. WILBUR.

ELECTRIC ARG LAMP. APPLIUATION rum) DBO. s, 1902.

2 SHEETs-SHEET 2.

30 MODEL.

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UNITED STATES Patented June '7, 1904.

PATENT OEEIcE.

MALCOLM H. BAKER, OF PITTSBURG, AND SAMUEL P. IVILBUR, OF WIL- KINSBURG, PENNSYLVANIA, ASSIGNORS TO IVESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

ELECTRIC-ARC LAMP.

SPECIFICATION forming part of Letters Patent No. 762,115, dated June '7, 1904.

Application filed December 6, 1902. Serial No. 134,072. (No model.)

To all whom it may concern:

Be it known that we, MALCOLM H. BAKER, a resident of Pittsburg, and SAMUEL P. IL- BUR, a resident of WVilkinsburg, in the county of Allegheny and State of Pennsylvania, citizens of the United States, have invented certain new and useful Improvements in Are- Lamps, of which the following is a specification.

One of the objects of the present invention is to produce an arc-lamp which shall have an increased trim life-that is, shall operate for an increased length of time with one supply or trim of electrodes.

A further object is to maintain a stable are which shall not be extinguished by the act of feeding or the feeding mechanism during operation.

A further object is to provide an electrode which shall be commercially of low cost and which need not be accurately shaped or gaged.

A further object is to eliminate all motion of mechanical parts during operation.

A further object is to produce a lamp of small mechanical dimensions which shall contain no clutches, dash-pots, or mechanicallymovable regulating and feeding parts.

A further object is to construct a lamp which may be operated in any position and which is not affected by swinging or vibration.

A further object is to combine great mechanical strength with small size and weight.

A further object is to produce a light giving no shadows, owing to the fact that the light is thrown downward.

A further object is to give to the bed-plate of the lamp a large cooling-surface adapted to receive the deposits from the consuming electrodes, and thereby to prevent an excessive deposit upon the lamp-globe.

While the present invention is applicable for use with electrodes either inclosed or exposed and of any desired composition, it is particularly adapted for use with electrodes composed of carbon mixed or associated with a percentage of metallic salts.

For carrying out the lnvention we employ electrodes in the form of broad plates of comparatively small length or vertical height. The large increase in cubical contents of such plates over the usual round or pencil electrodes produces the desired length of trim life.

The structure and operation of the lamp will be clearly understood by reference to the annexed drawings, in whiclr Figure 1 is an elevation of our improved lamp. Fig. 2 is a plan looking down upon the bed-plate, the lamp-top being removed; and Fig. 3 is a view looking upward toward the bottom of the bed-plate.

In the drawings, 1 and 2 are the plate-electrodes, clamped, respectively, within suitable holders 3 and 4. One of the holders, as 3, is fixed to the bed-plate 5 of the lamp, while the other holder is arranged to swing upon two pins or pivots 6 and 7 in supports 8 and 9, secured to the bed-plate on its under side.

By means of the pins or pivots 6 and 7 the electrode 4 may be turned or swung into contact with the electrode 3. A rod 10 extends from the holder 4: up through the bed-plate 5 and is attached to a flat spring 11. This spring carries the core 12 of a small series starting-magnet 13. A spring 14 holds this core normally out of the magnet 13, in which position the electrode 2 is pushed over into contact with the electrode 1 by the action of the spring 11 upon the rod 10. lVhen the lamp is thrown into circuit, the magnet 13, being in series with the electrodes, is energized, draws in its core 12, and separates the electrodes, moving the holder 4 out against a stop 15, secured to the under side of the bedplate 5. The electrode 2 remains in the position to which it is thus brought during the entire operation of the lamp.

In order to govern and regulate the arc and maintain the same in the proper position along the lower edges of the electrodes, two magnetic fields are provided. In the drawings two similar iron cores 16 and 17 are mounted, by means of arms 18 18 18 18 and angle-pieces, upon the bed-plate 5. These arms extend down through the bed-plate and are provided at the bottom with cross-pieces 19, 20, 21, and 22, so as to form two practically independent magnetic fields. In order to increase this independent action as between adjacent cross-pieces, the cross-pieces 19 and 20 and the cross-pieces 21 and 22 are separated, respectively, by thin brass strips. The core 16 carries a series winding of such direction that the field from the corresponding crosspieces 19 and 20 repels the arc downward. The core 17 carries a shunt-winding of such direction that the field from the cross-pieces 21 and 22 attracts the arc upward. In this manner a differential regulation is obtained.

In operation the arc is struck in the manner described and travels from point to point along the lower edges of the electrodes, seeking the path of least resistance. This results in the burning of the electrodes evenly in much the same manner as the ends of the carbons are burned away to even surfaces by the traveling of the arc in the ordinary inclosed arc-lamp. The are is spread out and regulated in voltage by the differential action of the magnetic fields as follows: Any increase in voltage is opposed by an increase in the strength of the shunt-field, which shortens the arc. Any decrease in voltage is opposed by a decrease in the strength in the shunt-field, thus permitting the series field to lengthen the are. It is thus obvious that the lamp operates without any mechanically moving or feeding parts.

In practice we find that the life of the electrodes is greatly increased by giving to the electrodes the general shape indicated in the drawings, as compared with the usual pencilelectrodes. For example, plates six inches long, two and one-half inches wide, and onefourth inch in thickness give fifty hours light on seven amperes of current as compared with sixteen hours light for pencil-electrodes twenty-four inches long and having approximately the same thickness or diameter. As to the shape of the electrodes, we may corrugate them or curve them to increase the cubic contents, and we may round the lower corners of the electrodes to prevent the declining of the are. We may also corrugate the lower surface of the bed-plate to increase the radiating and deposit-condensing area.

We may also place the cross-pieces forming the series magnetic field below the arc, the shunt remaining above, and thus place the are between the two fields. We may omit the series field entirely when using currents of twelve or more amperes, as with currents of this magnitude or greater ones the arc is spread out with sufficient intensity by the action of its own field.

By inclosing ordinary arc-lamp carbons in form of such plates as we have described within a suitable globe or container a life of five hundred hours-may be given to the lamp. With electrodes containing smaller or larger percentages of metallic salts the size of the inclosing globe or bulb will be proportionately increased and less and less care will be taken to provide a close fit for the inclosing parts.

We are aware that flat electrodes for arelamps are not broadly new in the art; but, so far as we know, it is novel to provide electrodes of flat or corrugated shape in which the length of the electrodes is normally greater than their height.

We claim as our invention In an arc-lamp, a pair of flat electrodes, each WM. H. QAPEL, GEORGE H. STOCKBRIDGE.

Signed by me, the aforesaid SAMUEL P.VvIL BUR, at East Pittsburg, in the county of Allegheny and State of Pennsylvania, this 28th day of November, A. D. 1902.

SAMUEL P. "WILBUR.

Witnesses:

WESLEY Gr. CARR, BIRNEY HINES. 

